Laminated composite electronic device including coil and capacitor

ABSTRACT

A laminated composite electronic device has a circuit including a coil and a capacitor within a laminate having a plurality of conductor layers laminated with an insulating layer interposed between the respective ones of the conductor layers. The device includes a coil conductor arranged on a first conductor layer and forming part of the coil, and a pair of capacitor electrodes for forming the capacitor, one of which is arranged on a second conductor layer such that the one capacitor electrode laps over the coil conductor when viewed from a laminating direction of the laminate, wherein the coil conductor forms part of the coil, and simultaneously serves as the other of the pair of capacitor electrode for forming part of the capacitor.

BACKGROUND OF THE INVENTION

The present invention relates to a laminated composite electronic deviceincluding a coil and a capacitor, and more particularly, to a compositeelectronic device which comprises a circuit including a coil and acapacitor within a laminate.

To respond to a demand for high-density mounting, composite electronicdevices are nowadays provided by containing a plurality of passiveelements within a single laminate chip to implement a variety offunctions.

For example, a laminated filter comprises a filter circuit composed of acoil and a capacitor within a laminate having a plurality of conductorlayers laminated with an insulating layer interposed between therespective conductor layers, thereby allowing for accomplishing suchfunctions as signal processing, EMC countermeasures, and the like. Thelaminated filter is widely employed in a variety of electronic equipmentsuch as a mobile telephone, a smart phone, a personal computer, and thelike.

The following patent documents disclose such laminated compositeelectronic devices:

Patent Document 1: JP-A-2012-29015;

Patent Document 2: JP-A-2012-29016;

Patent Document 3: JP-A-2012-60440; and

Patent Document 4: JP-A-2013-219469.

SUMMARY OF THE INVENTION

With a reduction in size and thickness and higher functions ofelectronic equipment progressively realized in recent years, electronicdevices employed in the electronic equipment are also required toprovide high performances and to have a smaller size and a lower height.However, a reduction in size and height of a device may result indifficulties in ensuring a sufficient space for mounting each circuitelement. As such, it is not easy to simultaneously provide a highperformance and a reduction in size and height.

For example, a reduction of a laminated low pass filter in size andheight will inevitably result in a smaller diameter of a coil and aconsequently lowering Q-value and inductance value, thus encounteringdifficulties in improving the performance.

FIGS. 17 and 18 show the structure of a conventional device which has alaminated coil L composed of coil conductors L11-L14 and a capacitor Ccomposed of capacitor electrodes C11, C12 disposed within internalconductor layers of a laminate. As shown in these figures, when the coilL and capacitor C are disposed side by side in the horizontal direction,the coil L is reduced in diameter, and moreover, the capacitor Cdisposed adjacent to the coil L prevents flux F of the coil L frompassing, possibly resulting in degraded characteristics of the coil Land inability to sufficiently satisfy required characteristics.

On the other hand, the requirement for simultaneous accomplishment ofsuch improved characteristics with the reduction in size and height isthought to be increased more and more in the future in step with thetrend of pursuing a reduction in size and height, more functions, andhigher functions for electronic equipment.

It is therefore an object of the present invention to provide a noveldevice structure for improving the characteristic of a coil in alaminated composite electronic device including a coil and a capacitor.

To solve the aforementioned problem and achieve the object, a laminatedcomposite electronic device according to the present invention has acircuit including a coil and a capacitor electrically connected to eachother within a laminate having a plurality of conductor layers laminatedwith an insulating layer interposed between the respective ones of theconductor layers. The device includes a coil conductor arranged on afirst conductor layer included in the plurality of conductor layers toconstitute at least a section of a conductor that forms part of thecoil; and a pair of capacitor electrodes for forming the capacitor,where one of the capacitor electrodes is arranged on a second conductorlayer included in the plurality of conductor layers different from thefirst conductor layer such that the one capacitor electrode laps overthe coil conductor when viewed from a laminating direction of thelaminate. The coil conductor forms part of the coil, and simultaneouslyserves as the other of the pair of capacitor electrodes for forming partof the capacitor.

In the laminated composite electronic device of the present invention,instead of arranging a coil and a capacitor side by side as in theaforementioned conventional structure (FIGS. 17 and 18), the capacitorelectrodes are arranged such that they lap over the coil conductorswithin an area in which the coil is arranged (see FIGS. 1 through 5later described), so that the present invention can save the area whichwould otherwise be required to arrange the capacitor, and cancorrespondingly increase the diameter of the coil to achieve a highinductance value. Additionally, the coil conductor can be increased inline width, thereby achieving a high Q-value. Furthermore, a chip can bereduced in size (reduction in size when viewed from the verticaldirection). For clarity, in this application, a description will be madewith a term “vertical direction” referring to a direction in whichlayers are laminated in a laminate, and a term “horizontal direction”referring to a direction parallel to each conductor layer and insulatinglayer.

Also, in the present invention, a coil conductor which forms part of thecoil also serves as one of a pair of electrodes (capacitor electrodes)which form a capacitor. Since the capacitor electrodes are arranged tooppose this coil conductor in the vertical direction, it is possible toprevent the flux of the coil from being blocked by the capacitorelectrodes.

For this purpose, the one capacitor electrode is preferably configuredto have a width equal to or smaller than a line width of the coilconductor (identical or less than the line width of the coil conductor),and to be fitted within the line width of the coil conductor withoutrunning off therefrom when viewed from the vertical direction.

In one typical aspect of the present invention, the coil includeslaminated coils which have coil conductors arranged on two or moreconductor layers, and the capacitor electrodes are arranged to besandwiched between these coil conductors.

More specifically, the laminated composite electronic device accordingto the present invention includes an other coil conductor different fromthe coil conductor arranged on the first conductor layer on a thirdconductor layer which is a conductor layer different from the firstconductor layer and the second conductor layer, wherein the other coilconductor is electrically connected to the coil conductor arranged onthe first conductor layer through an inter-layer connection conductor toform part of the coil together with the coil conductor arranged on thefirst conductor layer, the second conductor layer is a conductor layerlaminated between the first conductor layer and the third conductorlayer, and the one capacitor electrode arranged on the second conductorlayer is positioned between the coil conductor arranged on the firstconductor layer and the coil conductor arranged on the third conductorlayer.

Also, in another aspect of the present invention, a laminated coil isprovided as a coil in a similar manner to the foregoing aspect, but thecapacitor electrode is arranged on the top side (on the topmost layer)or on the bottom side (on the lowermost layer) of the coil, instead ofbetween coil conductors.

Specifically, the laminated composite electronic device according to thepresent invention includes an other coil conductor different from thecoil conductor arranged on the first conductor layer on a thirdconductor layer different from the first conductor layer and the secondconductor layer, wherein the other coil conductor is electricallyconnected to the coil conductor arranged on the first conductor layerthrough an inter-layer connection conductor to form part of the coiltogether with the coil conductor arranged on the first conductor layer,the second conductor layer is a conductor layer laminated on theopposite side to the third conductor layer from the first conductorlayer with respect to the laminating direction of the laminate, and theone capacitor electrode arranged on the second conductor layer ispositioned on the opposite side to the coil conductor arranged on thethird conductor layer from the coil conductor arranged on the firstconductor layer with respect to the laminating direction of thelaminate.

Further, in the present invention, in any of the laminated compositeelectronic device according to the present invention or aspects, boththe one capacitor electrode arranged on the second conductor layer andthe section of the coil conductor arranged on the first conductor layerand forming part of the other capacitor electrode may have an L-like ora U-like (C-like) plane shape (shape viewed from the verticaldirection).

While a coil conductor generally draws an L-like or U-like (C-like)pattern within a conductor layer, when a capacitor electrode is made tohave an L-like or U-like (C-like) plane shape so as to extend along thecoil conductor in such a shape, the coil conductor can be effectivelyutilized as a capacitor electrode to ensure a wide electrode area for acapacitor and achieve a sufficient capacitance.

Also, when a coil-integrated capacitor is designated for a capacitormade up of a capacitor electrode arranged to lap over a coil conductor,when viewed from the laminating direction of the laminate, and the coilconductor, as described above, in the present invention, the circuitimplemented in the laminate may include two or more capacitors and oneor more coil, where all the two or more capacitors may becoil-integrated capacitors.

It should be noted that the term “a circuit including a coil and acapacitor,” as used herein, is typically a filter circuit, but is notnecessarily limited to a filter circuit. This is because the presentinvention can be similarly applied to other circuits as long as they arecircuits including a coil and a capacitor.

According to the present invention, the characteristic of a coil can beimproved in a laminated composite electronic device including a coil anda capacitor.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and features of the present invention will become apparentfrom the following detailed description considered in connection withthe accompanying drawings. It should be apparent to those skilled in theart that the present invention is not limited to the undermentionedembodiment and a variety of modifications can be made within the scopeof the claims. In the drawings, wherein similar reference charactersdenote similar elements throughout the several views:

FIG. 1 is a perspective view showing an exemplary structure of anessential portion in a laminated composite electronic device accordingto a first embodiment of the present invention;

FIG. 2 is an exploded perspective view of the exemplary structure shownin FIG. 1;

FIG. 3 is a circuit diagram of the exemplary structure shown in FIG. 1;

FIG. 4 is a perspective view showing another exemplary structure of theessential portion of the laminated composite electronic device accordingto the first embodiment in an exploded view;

FIG. 5 is a circuit diagram showing the other exemplary structure shownin FIG. 4;

FIG. 6 is a perspective view showing another exemplary feature of acapacitor electrode;

FIG. 7 is a perspective view showing a further exemplary feature of acapacitor electrode;

FIG. 8 is a perspective view showing an exemplary modification to theessential portion of the laminated composite electronic device accordingto the first embodiment;

FIG. 9 is a perspective view showing another exemplary modification tothe essential portion of the laminated composite electronic deviceaccording to the first embodiment;

FIG. 10 is a circuit diagram showing a laminated composite electronicdevice according to a second embodiment of the present invention;

FIG. 11 includes plan views each showing a layer of a laminate in thelaminated composite electronic device according to the secondembodiment;

FIG. 12 is a graph representing an attenuation characteristic of thelaminated composite electronic device according to the secondembodiment;

FIG. 13 is a graph showing part of the graph represented in FIG. 12 inan enlarged view;

FIG. 14 includes plan views each showing a layer of a laminate in alaminated composite electronic device according to a third embodiment ofthe present invention;

FIG. 15A includes plan views each showing a layer (first conductor layerthrough sixth insulating layer) of a laminate in a laminated compositeelectronic device according to a fourth embodiment of the presentinvention;

FIG. 15B is a plan view showing a layer (seventh conductor layer) of thelaminate in the laminated composite electronic device according to thefourth embodiment;

FIG. 16 includes plan views each showing a layer of a laminate in alaminated composite electronic device according to a comparativeexample;

FIG. 17 is a perspective view showing an exemplary structure of anessential portion of a conventional laminated composite electronicdevice; and

FIG. 18 is an exploded perspective view of the exemplary structure shownin FIG. 17.

DESCRIPTION OF THE EMBODIMENTS

[First Embodiment]

First, characteristic features of the present invention will bedescribed as a first embodiment.

FIGS. 1-3 illustrate characteristic features in a laminated compositeelectronic device according to the present invention. As shown in thesefigures, the aforementioned convention structure (FIGS. 17 and 18)comprises a coil L and a capacitor C disposed side by side(horizontally), while the embodiment of the present invention comprisesa capacitor C between coil conductors L11, L12 which together form alaminated coil L by inserting a capacitor electrode C11 between the coilconductors L11, L12, and arranging the capacitor electrode C11 such thatit laps vertically over the coil conductor L11.

Specifically, a laminate is made up of five conductor layers including afirst conductor layer M1 through a fifth conductor layer M5 which arelaminated with an insulating layer (not shown) inserted between therespective conductor layers M1-M5. Loop-shaped coil conductors L11, L12,L13, L14 are disposed on the first conductor layer M1, third conductorlayer M3, fourth conductor layer M4, and fifth conductor layer M5,respectively, and are connected in order through via holes V (not shownin FIG. 1, and shown by broken lines in FIG. 2, and hereinafter simplycalled the “via”) to complete a spiral laminated coil L.

On a second conductor layer M2 which vertically adjoins the firstconductor layer M1 through an insulating layer, a capacitor electrodeC11 is arranged to vertically oppose the coil conductor L11 arranged onthe first conductor layer M1. This capacitor electrode C11 has anL-shaped plane shape and a width W1 which is equal to or less than aline width W2 of the coil conductor L11 (W1≤W2), such that the capacitorelectrode C11 laps over part of the loop-shaped coil conductor L11(partial line section of the coil conductor L11) arranged on the firstconductor layer M1. With such a structure, the capacitor C can be madeup of the capacitor electrode C11 arranged on the second conductor layerM2 and the coil conductor L11 arranged on the first conductor layer M1.The coil conductor L11 arranged on the first conductor layer M1 alsoserves as a capacitor electrode C12. Also, since the coil conductor L11also serves as the capacitor electrode C12, the coil L is electricallyconnected with the capacitor C.

Notably, in order to prevent variations (errors) of the capacitor C incapacitance due to a shift in position between the capacitor electrodeC11 and the coil conductor L11 (C12) possibly introduced by such causesas misalignment in the lamination of the conductor layers, preferably,the width W1 of the capacitor electrode C11 is smaller than the linewidth W2 of the coil conductor L11 (W1<W2), and the capacitor conductorC11 is fitted within the line width of the coil conductor L11. In otherwords, the entirety (whole width) of the capacitor electrode C11 ispreferably fitted between both edges (both ends in the width direction)of the coil conductor L11 in the width direction, when viewed from avertical direction.

Also, a dielectric film interposed in the coil integrated capacitor C(between the capacitor electrode C11 and the coil conductor L11 (C12)),i.e., the insulating layer (not shown) interposed between the firstconductor layer M1 and the second conductor layer M2 may be, forexample, a thin film mainly containing silicon nitride and alumina.

Then, as shown in FIG. 2, one end (an end opposite to an end which isconnected to the coil conductor L12 on the third conductor layer M3) ofthe coil conductor L11 on the first conductor layer M1 may be connectedto a terminal T1, and one end of the capacitor electrode C11 on thesecond conductor layer M2 and one end (an end opposite to an end whichis connected to the coil conductor L13 on the fourth conductor layer M4)of the coil conductor L14 on the fifth conductor layer M5 may berespectively connected to a terminal T2, resulting in that an LCparallel circuit can be completed, as shown in FIG. 3.

Alternatively, as shown in FIG. 4, the capacitor electrode C11 may bearranged on the bottom side of the lowermost coil conductor L14 to forma coil-integrated capacitor C between the capacitor electrode C11 andthe lowermost coil conductor L14, and the coil conductor L11 on thefirst conductor layer M1 may be connected to the terminal T1, and thecapacitor electrode C11 to the terminal T2, respectively, resulting inthat an LC series circuit is completed, as shown in FIG. 5, where thecoil L (coil conductors L11-L14) and the capacitor C (capacitorelectrodes C12, C11) are connected in series between the terminals T1and T2.

The capacitor electrode C11 may have, a U-like plane shape (C-like planeshape), for example, as shown in FIG. 6, in conformity to the shapepattern of the coil conductor, or may have a linear plane shape, forexample, a shown in FIG. 7. Further, as to a vertical position at whichthe capacitor electrode C11 may be arranged, instead of being arrangedbetween the coil conductor L11 and the coil conductor L12 as describedabove, the capacitor electrode C11 may also be arranged on the top sideof the topmost coil conductor L11, as shown in FIG. 8, to form thecapacitor C between the capacitor electrode C11 and the topmost coilconductor L11.

Alternatively, as shown in FIGS. 4 and 9 described above, the capacitorelectrode C11 may be arranged on the bottom side of the lowermost coilconductor L14 to form the capacitor C between the capacitor electrodeC11 and the lowermost coil conductor L14.

It should be noted that in this embodiment the coil L is made up of fourlayers of coil conductors L11-L14, but the coil may be made up of threeor less or five or more layers of coil conductors, or the coil canconsist of a single layer of coil conductor. Also, a variety of circuitsincluding a coil and a capacitor can be created by combining thestructure of this embodiment with the connection methods (FIGS. 3 and5).

[Second Embodiment]

A laminated composite electronic device according to a second embodimentof the present invention will now be described with reference to FIGS.10 through 13.

A laminated composite electronic device 11 according to the secondembodiment of the present invention is a laminated low-pass filter(hereinafter called the “LPF”) circuit, implemented in a chip, whichcomprises an LC filter made up of conductor patterns within a laminateincluding a plurality of conductor layers laminated with an insulatinglayer interposed between the respective conductor layers.

Specifically, as shown in FIG. 10, the circuit comprises two LC parallelcircuits (a first LC resonant circuit made up of a coil L1 and capacitorC2 connected in parallel with each other, and a second LC resonantcircuit made up of a coil L2 and a capacitor C4 connected in parallelwith each other) connected in series between an input terminal T1 and anoutput terminal T2; a capacitor C1 having one end connected between theinput terminal T1 and the first LC parallel circuit and the other endconnected to a ground terminal G; a capacitor C3 having one endconnected between the two LC parallel circuits and the other endconnected to the ground terminal G; and a capacitor C5 having one endconnected between the output terminal T2 and the second LC parallelcircuit and the other end connected to the ground terminal G.

The laminate has a rectangular plane shape, as shown in FIG. 11, andcomprises a first conductor layer M1, a first insulating layer I1, asecond conductor layer M2, a second insulating layer I2, a thirdconductor layer M3, a third insulating layer I3, a fourth conductorlayer M4, a fourth insulating layer I4, a fifth conductor layer M5, afifth insulating layer I5, and a sixth conductor layer M6, which arelaminated in order. The LPF according to this embodiment may compriseother conductor layers and insulating layers, not shown, for example, aconductor layer having a ground electrode and the like, in addition tothe respective layers shown in FIG. 11.

The laminate comprises, at four corners thereof (four corners whenviewed from the vertical direction), columnar conductors which extendvertically through the laminate from the first conductor layer M1through the sixth conductor layer M6. These conductors comprise terminalzones T1, T2, G, appearing on the respective conductor layers M1-M6, andvias V extending through the respective insulating layers I1-I5 forconnecting vertically adjoining terminal zones to each other to buildcolumnar terminals. When designating the adjacent corners as a firstthrough a fourth corner from the upper right corner of each layer in thecounter-clockwise direction in FIG. 11, a columnar input terminal (inputterminal zone T1) is positioned at the first corner; a columnar outputterminal (output terminal zone T2) at the second corner; and columnarground terminals (ground terminal zones G) at the third and fourthcorners of these four corners, respectively.

Notably, the ground terminal zone G on the first conductor layer M1 isformed such that the ground terminal zone G at the third corner and theground terminal zone G at the fourth corner continuously extend along along side (left side) of the first conductor layer M1, in order to formthe capacitor C3 (capacitor electrode C31, later described). Also,between the input terminal zone T1 and the output terminal zone T2,ground-side capacitor electrodes C11, C51 are arranged to form thecapacitors C1 and C5, respectively, and the capacitor electrodes C11,C51 are connected to the ground terminal zone G on the first conductorlayer M1 through a connection electrode E1. Further, a capacitorelectrodes C12, C52 are arranged on the second conductor layer M2 suchthat they oppose the capacitor electrodes C11, C51 respectively throughthe first insulating layer I1, where the capacitor C1 is made up of thecapacitor electrode C11 on the first conductor layer M1 and thecapacitor electrode C12 on the second conductor layer M2, and thecapacitor C5 is made up of the capacitor electrode C51 on the firstconductor layer M1 and the capacitor electrode C52 on the secondconductor layer M2.

Also, in one of two areas of the laminate equally divided in thelongitudinal direction, as viewed from the vertical direction of thelaminate (upper half of each layer in FIG. 11), a laminated coil L1 isarranged to forms part of the first LC resonant circuit. This laminatedcoil L1 is created by connecting in order loop-shaped coil conductorsL11, L12, L13, L14 respectively arranged on the first, third, fourth,and fifth conductor layers M1, M3, M4, M5 through vias V respectivelyextending through the first insulating layer I1, second conductor layerM2, second insulating layer I2, third insulating layer I3, and fourthinsulating layer I4.

Further, in the other of the two equally divided areas (lower half ofeach layer in FIG. 11), a laminated coil L2 is arranged to form part ofthe second LC resonant circuit. Like the laminated coil L1 describedabove, this laminated coil L2 is created by connecting in orderloop-shaped coil conductors L21, L22, L23, L24 respectively arranged onthe first conductor layer M1 and the third through fifth conductorlayers M3-M5 through vias V respectively extending through the firstinsulating layer I1, second conductor layer M2, and second throughfourth insulating layers I2-I4.

Notably, the laminated coil L1, which forms part of the first LCresonant circuit, is spirally routed downward such that it turnsclockwisely from the input terminal zone T1 arranged at the first cornerof the first conductor layer M1 toward the fifth conductor layer M5.Then, the laminated coil L1 is connected to the laminated coil L2 whichforms part of the second LC resonant circuit through a connectionelectrode E4 arranged on the fifth conductor M5 between both coils L1,L2. On the other hand, the laminated coil L2, which forms part of thesecond LC resonant circuit, is spirally routed upward such that it turnscounter-clockwisely from the connection electrode E4 on the fifthconductor M5 toward the first conductor layer M1, and connected to theoutput terminal zone T2 arranged at the second corner on the firstconductor layer M1.

Also, a capacitor electrode C32 is arranged on the second conductorlayer M2 so as to oppose a central area of the ground terminal zone Gcontinuously formed on the first conductor layer M1 through the firstinsulating layer I1. This capacitor electrode C32 forms the capacitor C3together with the ground terminal zone G (capacitor electrode C31) onthe first conductor layer. The capacitor electrode C32 is connected tothe respective laminated coils L1, L2 through the vias V formed throughthe second through fourth insulating layers I2-I4, electrodes E2arranged on the third through fifth conductor layers M3-M5, andconnection electrode E4 arranged on the fifth conductor layer M5.Connection electrodes E3 are arranged on the third and fourth conductorlayers M3, M4 for connecting the vias V to each other on the respectiveconductor layers M3, M5.

The capacitor C2 which forms part of the first LC resonant circuit, andthe capacitor C4 which forms part of the second LC resonant circuit arecoil-integrated capacitors as described above.

Specifically, a capacitor electrode C21 extending in an L-shape isarranged on the second conductor layer M2 so as to lap over a section ofthe coil conductor L11 on the first conductor layer M1. This capacitorelectrode C21 has a width smaller than the line width of the coilconductor L11, and is arranged to be fitted within the line width of thecoil conductor L11, when viewed from the vertical direction, opposite tothe coil conductor L11 to form the capacitor C2 therewith through thefirst insulating layer I1. Notably, the capacitor electrode C21 iscontinuous to a capacitor electrode C41, next described, for electricconnection. Also, the section of the coil conductor L11 opposite to thecapacitor electrode C21 is indicated by blacking out the section (thesame is applied to the coil-integrated capacitor as well). This sectionfunctions as the coil conductor L11 and simultaneously functions as thecapacitor electrode C22 which forms part of the capacitor C2. Also, thecoil L1 (coil conductor L11) is electrically connected to the capacitorC2 through this section of the capacitor electrode C22.

Likewise, the capacitor C4 comprises, on the second conductor layer M2,a capacitor electrode C41 which extends in an L-shape so as to lap overa section of the coil conductor L21 on the first conductor layer M1.This capacitor electrode C41 has a width smaller than the line width ofthe coil conductor L21, and is arranged to be fitted within the linewidth of the coil conductor L21, when viewed from the verticaldirection, opposite to the coil conductor L21 (blacked-out section C42)to form the capacitor C4 therewith through the first insulating layerI1. In this process, when the capacitor electrodes C21, C41 are chosento be smaller in width than the coil conductor L11, L21 and are fittedwithin the line width of the coil conductors L11, L21, as previouslydescribed, the capacitors C2, C4 can be prevented from experiencingcapacitance errors due to misalignment in lamination and the like. Also,the capacitors C2, C4 (capacitor electrodes C21, C41) will never blockthe flux of the coils L1, L2.

For comparison with this embodiment, a laminated LPF (comparativeexample) was created with a coil and a capacitor arranged side by sidein the horizontal direction as has been traditionally done. FIG. 16shows this comparative example. As shown in FIG. 16, the LPF accordingto this comparative example employs capacitors C1-C5, including acapacitor C2 included in a first LC resonant circuit and a capacitor C4included in a second LC resonant circuit, which are all implemented byconventionally known ordinary capacitors (which have two capacitorelectrodes opposite to each other), rather than coil-integratedcapacitors. These capacitors C1-C5 are arranged in a central area of thelaminate in the longitudinal direction, when viewed from the verticaldirection, and include laminated coils L1 (L11-L14) and L2 (L21-L24),respectively, on both sides of the capacitors C1-C5, i.e., on both endsof the laminate in the longitudinal direction, when viewed from thevertical direction.

FIGS. 12 and 13 are graphs representing the frequency-attenuationcharacteristic of the comparative example and the LPF according to thesecond embodiment. As is apparent from these graphs, it can be seenthat, according to the structure of this embodiment, an insertion losscan be reduced to improve the filter characteristic, as compared withthe comparative example. Also, as to the Q-value, the comparativeexample exhibits 14, while this embodiment exhibits 20 and can thusincrease the Q-value. These improved characteristics are thought to beaccomplished by virtue of the structure of the embodiment which allowsthe coils L1, L2 to be increased in diameter and the coil conductorsL11-L14, L21-L24 to be increased in line width.

[Third Embodiment]

A laminated LPF according to a third embodiment of the present inventionwill be described with reference to FIG. 14.

As shown in FIG. 14, the LPF of this embodiment, like the secondembodiment, employs coil-integrated capacitors for a capacitor C2 of afirst LC resonant circuit and a capacitor C4 of a second LC resonantcircuit, and in addition to these, employs coil-integrated capacitorsfor a capacitor C1 and a capacitor C5 as well.

Specifically, like the second embodiment, a coil conductor L11 formingpart of a coil L1 of the first LC resonant circuit, and a coil conductorL21 forming part of a coil L2 of the second LC resonant circuit arearranged on a first conductor layer M1. In this structure, a capacitorelectrode C11 of a capacitor C1 and a capacitor electrode C21 of acapacitor C2 are arranged on a second conductor layer M2 so as to opposethe coil conductor L11 of the first LC resonant circuit, thereby formingthe capacitor C1 between the capacitor electrode C11 and section C12 ofthe coil conductor L11, and forming the capacitor C2 between thecapacitor electrode C21 and another section C22 of the coil conductorL11.

Likewise, a capacitor electrode C41 of the capacitor C4 and a capacitorelectrode C51 of the capacitor C5 are arranged on the second conductorlayer M2 so as to oppose the coil conductor L21 of the second LCresonant circuit, thus forming the capacitor C4 between the capacitorelectrode C41 and section C42 of the coil conductor L21 and thecapacitor C5 between the capacitor electrode C51 and another section C52of the coil conductor L21, respectively. Notably, this embodimentdiffers from the second embodiment in that a ground terminal zone G ispositioned at a second corner, and an output terminal zone T2 ispositioned at a third corner, in order to implement the capacitors C1,C5 as coil-integrated capacitors.

[Fourth Embodiment]

A laminated LPF according to a fourth embodiment of the presentinvention will be described with reference to FIGS. 15A and 15B.

As shown in FIGS. 15A and 15B, the LPF of this embodiment employscoil-integrated capacitors for all capacitors C1-C5 included in an LPFcircuit (FIG. 3).

Specifically, like the third embodiment, the capacitor C1 and capacitorC2 are formed of a coil conductor L11 (C12, C22) of a first LC resonantcircuit arranged on a first conductor layer M1 and capacitor electrodesC11, C21 arranged on a second conductor layer M2, and additionally thecapacitor C4 and capacitor C5 are formed of a coil conductor L21 (C42,C52) of a second LC resonant circuit arranged on the first conductorlayer M1, and capacitor electrodes C41, C51 arranged on the secondconductor layer M2.

Further, for implementing the capacitor C3 as a coil-integratedcapacitor, a capacitor electrode C31 is arranged on a sixth conductorlayer M6 so as to lap over a coil conductor L14 which forms part of acoil L1 of the first LC resonant circuit arranged on a fifth conductorlayer M5, when viewed from the vertical direction. This capacitorelectrode C31 is connected to a ground terminal zone G arranged at thefourth corner of the sixth conductor layer M6, and opposes section C32of the coil conductor L14 arranged on the fifth conductor layer M5through the fifth insulating layer I5 to form the capacitor C3.

What is claimed is:
 1. A laminated composite electronic device having acircuit including a coil, a first capacitor and a second capacitorelectrically connected to one another within a laminate having aplurality of conductor lavers laminated with an insulating layerinterposed between respective ones of the plurality of conductor layers,said device comprising: a coil conductor arranged on a first conductorlayer included in said plurality of conductor layers, said coilconductor being at least a section of a conductor that forms is part ofsaid coil; a pair of capacitor electrodes for forming said firstcapacitor; and a pair of capacitor electrodes for forming said secondcapacitor, wherein one of said pair of capacitor electrodes for formingsaid first capacitor and one of said pair of capacitor electrodes forforming said second capacitor are arranged on a second conductor layerincluded in said plurality of conductor layers different from said firstconductor layer such that said one capacitor electrode for said firstcapacitor and said one capacitor electrode for said second capacitoroverlap with said coil conductor when viewed from a laminating directionof said laminate; said coil conductor comprises a loop-shaped conductor;and said loop-shaped conductor includes a first capacitor double-usearea that serves as an other capacitor electrode for said firstcapacitor, and a second capacitor double-use area that serves as another capacitor electrode for said second capacitor.
 2. The laminatedcomposite electronic device according to claim 1, wherein: one or bothof said one capacitor electrode for said first capacitor and said onecapacitor electrode for said second capacitor has a width equal to orsmaller than a line width of said coil conductor, and is completelyoverlapped with said coil conductor when viewed from the laminatingdirection of said laminate.
 3. The laminated composite electronic deviceaccording to claim 2, further comprising: an other coil conductordifferent from said coil conductor, arranged on a third conductor layerdifferent from said first conductor layer and said second conductorlayer, wherein said other coil conductor is electrically connected tosaid coil conductor through an inter-layer connection conductor to formpart of said coil together with said coil conductor; said secondconductor layer is laminated between said first conductor layer and saidthird conductor layer; and said one capacitor electrode for said firstcapacitor and said one capacitor electrode for said second capacitor arepositioned between said coil conductor and said other coil conductor. 4.The laminated composite electronic device according to claim 1, furthercomprising: an other coil conductor different from said coil conductor,arranged on a third conductor layer different from said first conductorlayer and said second conductor layer, wherein said other coil conductoris electrically connected to said coil conductor through an inter-layerconnection conductor to form part of said coil together with said coilconductor; said second conductor layer is laminated between said firstconductor layer and said third conductor layer; and said one capacitorelectrode for said first capacitor and said one capacitor electrode forsaid second capacitor are positioned between said coil conductor andsaid other coil conductor.
 5. The laminated composite electronic deviceaccording to claim 1, wherein: both said one capacitor electrode forsaid first capacitor and said first capacitor double-use area have anL-like plane shape.
 6. The laminated composite electronic deviceaccording to claim 5, wherein: both said one capacitor electrode forsaid second capacitor and said second capacitor double-use area have anL-like plane shape.
 7. The laminated composite electronic deviceaccording to claim 5, wherein: both said one capacitor electrode forsaid second capacitor and said second capacitor double-use area have aU-like plane shape.
 8. The laminated composite electronic deviceaccording to claim 1, wherein: both said one capacitor electrode forsaid first capacitor and said first capacitor double-use area have anU-like plane shape.
 9. The laminated composite electronic deviceaccording to claim 1, wherein: said circuit is a filter circuit.